Spark plug having concentric radially spaced electrodes



H. BAUM April 4, 1967 SPARK PLUG HAVING CONCENTRIC RADIALLY SPACED ELECTRODES Filed May 13, 1964 INVENTOR Hermon Baum ATTORNEY United States Patent 3,312,848 SPARK PLUG HAVING CONCENTRIC RADIALLY SPACED ELECTRODES Herman Baum, 3705 Autumn Drive, Fort Worth, Tex. 76109 Filed May 13, 1964, Ser. No. 367,122 3 Claims. (Cl. 313-115) This invention relates to spark plugs for internal combustion engines, and it has particular reference to spark plugs having concentric radially spaced electrodes.

The principal object of the invention resides in the provision of a spark plug of simple and economical design, having a minimum of parts but capable of maximum sparking efiiciency.

Spark plugs of conventional design, and employed almost universally in automotive type engines, have a single spark gap confined to a relatively finite area centrally of the plug base and, due to the limited space between the electrodes, accumulations of carbon deposits and oil therein impair the effectiveness thereof. In addition, several different types or classifications of the conventional plugs are required to afford suitable combustion specifications for the variety of classes and sizes of engines used in the difierent types of automotive vehicles or for stationary power.

It is well known that the common plug, having the single central spark gap, is subjected to intense working temperatures which tend to rapidly diminish its serviceability requiring frequent replacement. Such conventional spark plugs are based upon the principle of thermal cleansing and for this reason are designed to function at predetermined high working temperatures, otherwise the spark gap will become fouled with carbon and oily sludge.

An important object of the invention is that of providing a sparkplug capable of producing a circular flame, which ignites the combustibles with greater efiicicncy and rapidity than the single concentrated spark gap of the conventional plug, and by reason of this radial flame, a more thorough cleansing action is assured since carbon, engine oil, and other non-combustible elements, cannot accumulate between the electrodes to prevent proper function of the plug.

It is a further object of the invention to provide a spark plug embodying features which aiTord constant air circulation about its base, tending to minimize heating and thus insuring more efiicient operation for considerably longer periods than is possible by the use of conventional spark plugs having a central concentrated spark gap.

While the foregoing objects are paramount, other and lesser objects will become apparent as the description proceeds when considered in connection with the appended drawings wherein:

FIGURE 1 is an elevational view of a spark plug embodying the invention.

FIGURE 2 is a longitudinal sectional view showing the ceramic insulator, the ported base, the dual arrangement of cylindrical electrodes concentrically arranged about the central electrode, and the cooling ribs formed on the insulator.

FIGURE 3 is a transverse sectional view, on line 3-3 of FIGURE 2, showing the enlarged head of the concentric electrode, and

FIGURE 4 is a fragmentary illustration, in partial section, showing a single cylindrical electrode arranged about the central electrode.

The invention, in its preferred form, comprises a base having a threaded shank portion 11 adapted to be secured in the cylinder head (not shown) of an internal combustion engine and in communication with the combustion chamber thereof. Formed about the shank portion 11 is a shoulder 12 which is seated upon a suitable gasket (not shown) to provide a seal.

A ceramic insulator 13 is arranged in the chamber 14 formed in the base 10, its body portion 15 having a series of circumferential grooves 16 formed thereon to define a plurality of cooling fins 17 therebetween, and the surrounding wall 18 of the base 10 has a series of ports 19 arranged circumferentially thereof opposing the fins 17 whereby the latter are exposed to the atmosphere about the base 10, an annular air space 20 being provided internally of the chamber 14 about the body portion 15 of the insulator 13.

The insulator 13 has a depending downwardly tapered portion which extends into the internally tapered shank portion 11 of the base 10 and a shoulder 22 is defined therearountl beneath the body portion 15 of the insulator 13 and is seated on a gasket 23, the function of which will become apparent. A gasket 24 is seated about the shoulder 25 defined around the neck portion 26 of the insulator 13 against which the internal flange 27 of the base 10 impinges when the insulator 13 is assembled with the base 10, as shown in FIGURE 2.

The insulator 13 has a concentric bore 28 therein at the upper end of which is an enlarged concentric recess 29. The bore 28 extends into the body portion 15 and communicates with a concentric recess .30, in the lowermost end of the portion 21, through a bore 31 whose diameter is substantially less than that of the bore 23 and the recess 30, a shoulder 32 being defined in the latter about the bore 31.

A central electrode is arranged within the insulator 13 and comprises upper and lower sections 33 and 34. The upper section 33 has a head member 35 which is received in the recess 29 and is seated against a spring 36 arranged about the shoulder 37 defined in the recess 29, as shown in FIGURE 2. A threaded spindle 38 is formed with the head 35 and is adapted to receive a nut 39 for the attachment of an ignition wire (not shown).

The lower section 34 of the central electrode is formed with a head member 40, the body of which is substantially greater in diameter than the stem whereby to define a shoulder 41 therearound which is seated against a gasket 42 arranged in the recess 30 and about the shoulder 32 therein. The sections 33 and 34 of the central electrode are connected by threading the upper end of the latter into the internally threaded socket 43 in the lower end of the upper section 33, as shown in FIG- URE 2. The lowermost end of the head member 46 of the lower section 34 of the electrode is flared outwardly forming a disk-shaped sparking element 44 which has a parabolical face 45, as illustrated in FIGURES 2 and 4, and extends below the shank portion 11 of the base 10.

In conventional spark plugs the central electrode, or point, ordinarily extends slightly below the body or base of the plug and terminates adjacent to or near a fixed ground electrode integral with the lowermost rim of the base to provide a spark gap. The present invention is designed to provide a radial spark gap producing a circular flame.

In the preferred form of the invention the shoulder 22 of the insulator 13 is seated upon the radial flange 46 of a ceramic insulator sleeve 47 which surrounds the tapered depending member 21 and is coextensive therewith, as shown in FIGURE 2. A metallic cylindrical electrode 48, which is slightly conical embraces the member 21 internally of the ceramic sleeve 47 and extends below the lower ends of both of these elements concentrically of the hollow shank portion 11 of the base 10 terminating at the lower end thereof.

The lowermost end of the cylindrical electrode 43 is flared outwardly to provide a flange 49 therearound which surrounds and is spaced from the head 40 of the lower section 34 of the central electrode and is concentric with the disk-shaped sparking element 44 to define a primary annular spark gap between the latter and the element 43. The gasket 23 provides a seal between the shoulder 22 of the insulator 13 and the top of the ceramic sleeve 47 on which the insulator is supported.

Surrounding the ceramic sleeve 47 is another metallic cylindrical electrode 50 which also provides a lining for the internally tapered shank portion 11 of the base 10. The cylindrical electrodes 48 and 50 are thus spaced apart by the ceramic sleeve 47 so as to define an annulus 51 between them, as apparent in FIGURE 2, and a secondary annular spark gap 52 between the lowermost ends of the cylindrical electrodes 48 and 50. A gasket 53 is arranged in the bottom of the chamber 14 and is engaged by the radial flange 46 of the ceramic sieeve 47.

It is desirable to minimize direct contact between the ceramic insulator 13 and the central electrode to reduce heat transference between these elements. The external diameters of the upper and lower sections 33 and 34 of the central electrode are thus slightly less than the internal diameters of the bores 28 and 31 to provide annular spaces therearound.

In FIGURE 4 is illustrated a modified form of the invention wherein the tapered portion 21 of the ceramic insulator 13 has a greater diameter than that shown in FIGURE 2, and the ceramic sleeve 47 is omitted. The element conformably embraces the lower portion 2.1 of the insulator 13 and is seated in the internally tapered shank portion 11 of the base 10, providing an annular spark gap 54 therearound.

The invention is manifestly capable of certain changes and modifications in structure and design without departing from the spirit thereof or the scope of the appended claims.

What is claimed is:

1. In a spark plug for internal combustion engines, having a base formed with a hollow body portion and '9. depending shank portion, the said base having a series of ports formed about said body portion, and a ceramic insulator arranged concentrically of said base and having a series of spaced circumferential ribs exposed to the ports in the body portion of said base, and having a portion depending into said shank portion, the improvements comprising: a central electrode, having upper and lower threadedly joined sections, arranged concentrically of said insulator, the lower section extending beyond the lowermost end of said insulator and through said shank portion defining an annular chamber therearound within said shank portion, a first conical electrode in said shank portion providing a liner therefor and a conical ceramic sleeve seated in said conical electrode, the said ceramic sleeve having an annular flange about its upper end providing a seat for said ceramic insulator, a second conical eiectrode seated in said sleeve and embracing the lower end of said insulator defining an annular space therearound internally of said first conical electrode below the lower end of said insulator, and a circular sparking element formed on the lowermost end of the lower section of said central electrode and concentrically spaced from the lower ends of said first and second conical electrodes providing a circular spark gap therearound.

2.. In a spark plug as described in claim 1, wherein the said first conical electrode is extended beyond the lower end of the shank portion of said base, and the second conical electrode has a flared lower end arranged about said circular sparking element whereby to provide a primary annular spark gap between said second conical electrode and said sparking element.

3. In a spark plug as described in claim 1, wherein seating gaskets are arranged between the lower end of said ceramic insulator and the top surface of the flange on said ceramic sleeve, and beneath said flange, respectively.

References Cited by the Examiner UNITED STATES PATENTS 1,961,240 6/1934 Main 313-438 X 2,064,089 12/1936 Stemmeler 3l3136 X 2,081,501 5/1937 Nowosieiski 313-ll.5

JAMES W. LAWRENCE, Primary Examiner. C. R. CAMPBELL, Assistant Examiner. 

1. IN A SPARK PLUG FOR INTERNAL COMBUSTION ENGINES, HAVING A BASE FORMED WITH A HOLLOW BODY PORTION AND A DEPENDING SHANK PORTION, THE SAID BASE HAVING A SERIES OF PORTS FORMED ABOUT SAID BODY PORTION, AND A CERAMIC INSULATOR ARRANGED CONCENTRICALLY OF SAID BASE AND HAVING A SERIES OF SPACED CIRCUMFERENTIAL RIBS EXPOSED TO THE PORTS IN THE BODY PORTION OF SAID BASE, AND HAVING A PORTION DEPENDING INTO SAID SHANK PORTION, THE IMPROVEMENTS COMPRISING: A CENTRAL ELECTRODE, HAVING UPPER AND LOWER THREADEDLY JOINED SECTIONS, ARRANGED CONCENTRICALLY OF SAID INSULATOR, THE LOWER SECTION EXTENDING BEYOND THE LOWERMOST END OF SAID INSULATOR AND THROUGH SAID SHANK PORTION DEFINING AN ANNULAR CHAMBER THEREAROUND WITHIN SAID SHANK PORTION, A FIRST CONICAL ELECTRODE IN SAID SHANK PORTION PROVIDING A LINER THEREFOR AND A CONICAL CERAMIC SLEEVE SEATED IN SAID CONICAL ELECTRODE, THE SAID CERAMIC SLEEVE HAVING AN ANNULAR FLANGE ABOUT ITS UPPER END PROVIDING A SEAT FOR SAID CERAMIC INSULATOR, A SECOND CONICAL ELECTRODE SEATED IN SAID SLEEVE AND EMBRACING THE LOWER END OF SAID INSULATOR DEFINING AN ANNULAR SPACE THEREAROUND INTERNALLY OF SAID FIRST CONICAL ELECTRODE BELOW THE LOWER END OF SAID INSULATOR, AND A CIRCULAR SPARKING ELEMENT FORMED ON THE LOWERMOST END OF THE LOWER SECTION OF SAID CENTRAL ELECTRODE AND CONCENTRICALLY SPACED FROM THE LOWER ENDS OF SAID FIRST AND SECOND CONICAL ELECTRODES PROVIDING A CIRCULAR SPARK GAP THEREAROUND. 